Year	Percent
1976	8.16
1977	8.34
1978	11.17
1979	7.1
1980	7.51
1981	5.44
1982	6.93
1983	7.21
1984	12.93
1985	14.19
1986	12.99
1987	13.17
1988	12.64
1989	9.15
1990	6.07
1991	6.58
1992	20.59
1993	21.63
1994	18.39
1995	16.62
1996	11.71
1997	11.41
1998	8.53
1999	7.89
2000	7.49
2001	8.01
2002	8.5
2003	9.53
2004	8.72
2005	7.43
2006	7.72
2007	6.45
2008	6.88
2009	10.15
2010	10.9
2011	9.8
2012	10.95
2013	11.66
2014	11.81
2015	12.35
2016	9.26